Mount Prospect, Illinois 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

859
FXUS63 KLOT 082338
AFDLOT

Area Forecast Discussion
National Weather Service Chicago/Romeoville, IL
638 PM CDT Fri May 8 2026

.KEY MESSAGES...

- Occasional chances for scattered rain showers will continue
  into next week.

- Temperatures will gradually warm through Saturday before
  trending cooler Sunday into early next week.

&&

.DISCUSSION...
Issued at 151 PM CDT Fri May 8 2026

A quasi stationary front is currently draped across the Central
Plains from Topeka to Chicago. To the north of the boundary, a
cooler air mass with light cumulus clouds bubbling along the
northern periphery. To the south, better warm air advection
allowing for showers to move from west to east south of
Interstate 80. Chances for thunder cannot be completely ruled
out for areas near and south of US-24 this afternoon/early
evening, but any (if at all) that does occur should be isolated.
Lastly, a weak lake breeze has developed. Models are suggesting
that it will have a hard time moving farther inland than Cook
County, but it could be a favored area for isolated showers to
develop, particularly in northwest Indiana being closer located
to the front.

Through the weekend, an upper level low hovering over the
southern Hudson Bay will dictate the weather pattern, namely
continued northwest flow over Chicago with smaller perturbations
traveling around the larger upper level low. One such wave is
expected to pass over the area overnight tonight. Some of the
mid-level moisture might show up as returns on radar, but weak
forcing and low level dry air prevented any formal mention of a
chance of rain into tomorrow morning. Another wave will most
likely traverse the upper level low tomorrow late morning
through the afternoon sending a surface cold front over northern
Illinois. Hi-res models are showing a little bit agreement on
slightly better forcing with this wave to prompt a slight (15 to
24 percent) chance for rain. However, with RHs in the 30s,
there is lower confidence in whether or not the rain will make
it to the ground or just materialize as virga. So shower
coverage may be more spotty in nature tomorrow as the wave moves
southward. By Saturday night the upper level low will begin to
slowly move east. Shower chances will focus Saturday evening
south of I-80 and eventually move south and east. Weak upper
level ridging and height rises should allow for a drier Sunday
for Mother`s Day. However, winds will turn northerly allowing
for a cooler air mass to move in. High temperatures will go from
the 70s on Saturday to just the low 60s on Sunday.

The ridging appears to be short lived as the next upper level
trough may descend down out of Canada Monday night and provide
the next chance for rain on Tuesday. Cooler temperatures are
expected to remain through the midweek, but a potential warm
stretch may be in store for the end of the work week next week.

DK

&&

.AVIATION /00Z TAFS THROUGH 06Z SUNDAY/...
Issued at 638 PM CDT Fri May 8 2026

Aviation forecast concerns for the 00Z TAFs:

- East-southeast lake breeze winds at ORD/MDW will diminish and
  gradually turn south through this evening.

- Breezy west-northwest winds develop Saturday, with gusts 20-25
  kt in the afternoon.

- Low (~20%) chance of showers Saturday afternoon.

Evening surface analysis depicts surface low pressure passing
north of Lake Superior, with a cold frontal trough trailing
through the upper Mississippi Valley into the plains. Modest
southwest gradient winds across the local area have allowed a
lake breeze to push inland through GYY/MDW/ORD, which has
stalled just to the west of ORD/MDW. Lake breeze circulation
will decay this evening, allowing surface winds to diminish and
gradually become south-southwest.

The aforementioned weak cold front will push across the area
Saturday morning, producing a wind shift to the west, with some
gusts in the 15-20 kt range by midday. A second cold frontal
boundary will move through the area in the afternoon in
association with a mid-level disturbance tracking across the
upper Midwest. This second front will further shift winds west-
northwest and increase gusts into the 20-25 kt range during the
afternoon. There is a low (~20%) chance of showers with this
disturbance Saturday afternoon, though too low for TAF mention
at this time.

Ratzer

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...None.
IN...None.
LM...None.

&&

$$

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